According to the demand of stable operation for smart grid dispatching and control system, online monitoring and intelligent diagnostic platform technology scheme for operating states of smart grid dispatching and control system is proposed. And specific solutions are provided to such key technologies as the states information acquisition, system health evaluation, system failure analysis and positioning, etc. The scheme has been pilot applied in the control center. Practice shows that it is capable of achieving operating states monitoring, evaluation, early warning and failure precognition of grid dispatching and control system. The scheme has improved the level of maintenance and management to ensure the stable operation of the system, as well as guaranteeing the safety and stability of the grid. This work is supported by Science and Technology Project of State Grid Corporation of China (No. 5442DZ160031).